When a T. rex pursues a jeep in the movie Jurassic Park, we see a reflected image of the (very large) T. rex via a side-view mirror, on which is printed the (then darkly humorous) warning: "Objects in mirror are closer than they appear." Is the mirror flat, convex, or concave? Why do you think so?

Note to the instructor: This is trickier than it appears on the surface. There are two (relevant) ways that we judge the distance of an object: by parallax, and by size, knowing about how big it really is. In this example, the two ways do not agree, and the one naturally reached for by some physicists (the distance measurement in the mirror equation) is not the relevant one here.